This invention relates to methods and preparations for cleansing, specifically to methods and compositions that do not irritate the skin.
Cleansing products come in many types and forms, but are generally divided into personal care cleansers and household cleansers. The personal care cleansers most commonly thought of by consumers are skin cleansers (including bar soaps) and shampoos. However, this class of product also includes body washes, personal hygiene cleansers, contact lens cleansers, dental cleansers, facial cleansers, and makeup removers (including eye makeup removers). The general class of household cleansers includes laundry detergents, hard surface cleansers, porous surface cleansers, dishwashing detergents, window cleansers, scouring cleansers and disinfectant cleansers. Although each of these products contains a specific set of specialized ingredients depending upon the particular end use of the product, they all contain surfactants.
The most common type of cleansing product is a liquid or a powder formulation. However, cleansing products can also be in such forms as an aerosol, a mousse, a gel, an emulsion, a discrete packet, or impregnated on a towelette. Although these cleansers come in many different forms, they all have in common the presence of a surfactant.
In view of their ubiquitous use, surfactants in cleansing products often come into contact with human skin. Although this contact may be brief or even secondary (as for instance clothing washed with laundry detergent), it is desirable that cleansing products have a minimal dermatologic effect. Unfortunately, surfactants often cause irritation, dryness, cracking and peeling of the skin. Additionally, there are known case reports in the dermatological literature documenting allergic dermatitis in response to contact with a cleansing product. The allergic reaction can be caused by the fragrance contained in the cleansing product, or by the surfactant itself. In general, if a surfactant system can be applied directly to human skin without causing irritation, it will be safe for use in products used to cleanse materials that contact the skin (such as laundry detergent), or in products with limited direct contact with the skin (such as household products, including hard surface cleansers, window cleansers, and automotive cleansers).
Numerous patents have issued which concern cleansing products that include surfactants, and mixtures of surfactants, which are designed to be mild to the skin (e.g., U.S. Pat. No. 5,908,617; U.S. Pat. No. 5,785,979; U.S. Pat. No. 5,663,137; U.S. Pat. No. 5,632,978; U.S. Pat. No. 5,567,359; U.S. Pat. No. 5,562,912; U.S. Pat. No. 5,480,633; U.S. Pat. No. 5,322,643; U.S. Pat. No. 5,252,246; U.S. Pat. No. 5,096,608; U.S. Pat. No. 5,084,212; U.S. Pat. No. 5,073,293; U.S. Pat. No. 5,015,414; U.S. Pat. No. 4,968,450; U.S. Pat. No. 4,812,253; U.S. Pat. No. 4,673,525). However, each of these formulations has limitations. These limitations include limited foam volume, an undesired skin feel of the foam, instability, etc. that require the addition of other agents, some of which are not commercially available. Thus there is a need for a surfactant composition that is mild to the skin and eyes and can be easily produced.
A surfactant composition has been discovered that is mild to the skin, leaves the skin barrier intact, is stable, can be formulated into any type of cleansing preparation, and uses commonly available surfactants. In addition to being gentle to the skin, the surfactant composition is extremely mild to eye tissue, and is therefore suitable for contact lens solutions or other cleansers (such as shampoos) that contact the eye. The surfactant composition has a stable viscosity and an acceptable skin feel without the addition of polymeric materials.
A composition for cleansing is disclosed. The composition includes at least about 2% of a mixture of a salt of an alkyl sulfoacetate and a salt of an ethoxylated alkyl sulfosuccinate, at least about 3% of a salt of an ethoxylated alkyl sulfate, at least about 1% of an amphoteric surfactant, at least about 0.05% of an alkyl glucoside, and at least about 0.005% of a phospholipid.
A cleansing composition is also disclosed that includes about 2% to about 70% of a mixture of a salt of an alkyl sulfoacetate and a salt of an ethoxylated alkyl sulfosuccinate, about 3% to about 40% of a salt of an ethoxylated alkyl sulfate, about 1% to about 40% of an amphoteric surfactant, about 0.05% to about 10% of an alkyl glucoside, and about 0.005% to about 10% of a phospholipid.
In addition, a cleansing composition is disclosed that includes about 41% of a mixture of alkyl sulfoacetate and ethoxylated alkyl sulfosuccinate, about 34% of an ethoxylated alkyl sulfate, about 22% of an amphoteric surfactant, about 2% of an alkyl glucoside, and about 0.5% of a phospholipid.
A method of cleaning, including contacting a surface to be cleansed with a composition of the invention, is also described. The invention also includes cleansing compositions to which the surfactant has been added.
The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description of particular embodiments.
Compositions including a combination of surfactants have been found that are very mild (gentle) to the skin and eye tissues such that they cause minimal, if any, irritation of these tissues. Although materials contained in the compositions are generally recognized as safe, the combination causes less irritation to the tissues than would be expected based on the irritation caused by the components individually. The compositions do not require the presence of any known anti-irritant compounds to achieve the level of safety found.
The compositions are unique for several additional reasons. They do not require the presence of ancillary materials to achieve levels of foam generally desired by consumers, and do not require the presence of polymeric materials to achieve a stable viscosity or skin feel often desired by consumers. Moreover, the compositions do not require the presence of solubilizers and stabilizers to achieve a suitable product shelf life, even when stored at the extremes of temperature, such as high temperatures (as high as 50xc2x0 C.) or low temperatures (less than 4xc2x0 C.). This combination of effects is both unexpected and unique among surfactants.
The terms xe2x80x9caxe2x80x9d and xe2x80x9cthexe2x80x9d include the plural as well as the singular, unless the context clearly indicates otherwise.
The term xe2x80x9csurfactantxe2x80x9d refers to a surface-active agent that reduces surface tension when dissolved in water or an aqueous solution, or which reduces interfacial tension between two liquids, or between a liquid and a solid. Detergents, wetting agents and emulsifiers are examples of surfactants.
An xe2x80x9camphotericxe2x80x9d surfactant refers to a surfactant that has the capacity of behaving either as an acid or a base. Specific, non-limiting examples of an amphoteric surfactant are betaine, sultaine, hydroxysultaine, imidazoline, aminoalkanoate, and iminoalkanoate surfactants.
The term xe2x80x9cphospholipidxe2x80x9d refers to a lipid compound that yields on hydrolysis phosphoric acid, an alcohol, a fatty acid, and a nitrogenous base. Phospholipids include, but are not limited to, Coco Phosphatidyl PG-Dimonium Chloride, Linoleamidopropyl Phosphatidyl PG-Dimonium Chloride, Cocamidopropyl Phosphatidyl PG-Dimonium Chloride, Borageamidopropyl Phosphatidyl PG-Dimonium Chloride, Stearamidopropyl Phosphatidyl PG-Dimonium Chloride, lecithin, and derivatives of lecithin.
The term xe2x80x9calkylxe2x80x9d refers to a cyclic, branched, or straight chain alkyl group containing only carbon and hydrogen, and unless otherwise mentioned contains one to thirty carbon atoms. This term is further exemplified by groups such as methyl, ethyl, n-propyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, adamantyl, and cyclopentyl. Alkyl groups can either be unsubstituted or substituted with one or more substituents, e.g. halogen, alkyl, alkoxy, alkylthio, trifluoromethyl, acyl, acyloxy, hydroxy, mercapto, carboxy, aryloxy, aryl, arylalkyl, heteroaryl, amino, alkylamino, dialkylamino, morpholino, piperidino, pyrrolidin-1-yl, piperazin-1-yl, or other functionality.
The term xe2x80x9clower alkylxe2x80x9d refers to a cyclic, branched or straight chain monovalent alkyl radical of one to seven carbon atoms. This term is further exemplified by such radicals as methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, i-butyl (or 2-methylpropyl), cyclopropylmethyl, i-amyl, n-amyl, hexyl and heptyl. Lower alkyl groups can also be unsubstituted or substituted. The term xe2x80x9chigher alkylxe2x80x9d refers to a cyclic, branched or straight chain monovalent alkyl radical of eight to thirty carbon atoms. Higher alkyl groups can also be unsubstituted or substituted.
The term xe2x80x9cglycosidexe2x80x9d refers to an organic compound which can be reduced by hydrolysis into sugars and other organic substances, known as glycones. The term xe2x80x9cglucosidexe2x80x9d refers to a glycoside which has glucose as the sugar constituent. An xe2x80x9calkyl glucosidexe2x80x9d includes the linear or branched chain alcohols, including but not limited to those from coconut oils, palm oils, etc. or mixtures thereof.
xe2x80x9cHydroxylxe2x80x9d refers to xe2x80x94OH.
xe2x80x9cAlcoholxe2x80x9d refers to R-OH, wherein R is alkyl, especially lower alkyl (for example in methyl, ethyl or propyl alcohol), but can also be a higher alcohol (for example decyl or dodecyl). An alcohol may be either linear or branched, such as isopropyl alcohol.
xe2x80x9cCarboxylxe2x80x9d refers to the radical xe2x80x94COOH, and substituted carboxyl refers to xe2x80x94COOR where R is alkyl, lower alkyl or a carboxylic acid or ester.
xe2x80x9cSaltxe2x80x9d refers to the compound formed when the hydrogen of an acid is replaced by a metal or its equivalent (e.g., an NH4 radical). The salts include the monovalent ions (lithium, sodium and potassium, etc.), the divalent ions (barium, calcium etc.), the trivalent ions (aluminum, etc.), or the ammonium based ions (ammonium, monoalkyl-, dialkyl-, and trialkylammonium ion, such as triethanolammonium ion) or mixtures thereof.
Other chemistry terms herein are used according to conventional usage in the art, as exemplified by The McGraw-Hill Dictionary of Chemical Terms (1985) and The Condensed Chemical Dictionary (1981).